The subject matter disclosed herein relates generally to electrical generators and motors, and more specifically, to electrical turbo-generators.
In general, electricity may be generated by inducing a current on a set of armature windings as a result of the relative motion of a nearby magnetic field. In order to produce this field, some electrical generators may inject a large amount of current (e.g., 1-5 kA) into the field windings of a spinning rotor during operation. Such electrical generators may use collector assemblies, also known as rotating slip ring assemblies, positioned about the rotor and electrically coupling the rotor to a stationary exciter via a number of stationary brushes. Accordingly, these brushes provide conductive paths between the stationary exciter and the spinning rotor such that power may be transmitted to the rotor and the rotating field may be produced. However, during operation, if one or more brushes lose contact with the collector ring, arcing events may occur. For example, a brush and collector ring may arc due to physical wear on the brush and/or ring, excessive vibration of the shaft, the presence of contaminants (e.g., particulates or oil) between the brush and ring, or incorrect brush alignment or installation.
Due to the large voltages and currents operating within many generators, arcing events may cause substantial damage to the collector ring and brushes over time, eventually resulting in a flashover event. During a flashover event, a short circuit path may form within the rotor between the positive and negative terminals of the exciter, between the positive terminal of the exciter and ground, and/or between the negative terminal of the exciter and ground. Generally speaking, a flashover event results in a catastrophic failure of the generator, leaving the generator inoperable. Furthermore, a flashover event may cause substantial damage to other electrical components coupled to the generator as well as personnel or equipment that may be physically located near the generator. In general, regularly scheduled inspection and maintenance of a generator is often required in order to verify the integrity of the brush/slip ring assembly and minimize the risk of flashover.
However, regularly scheduled inspection and maintenance of a generator is costly. In general, much of the inspection and maintenance of a generator may actually be performed while the generator continues to operate, increasing the complexity and safety risks of such maintenance. Furthermore, reliance on such a maintenance schedule only takes the operational time of the equipment into consideration, and fails to prioritize maintenance based on device performance or other indicators. That is, for strictly schedule-based maintenance, a healthy generator may receive largely unneeded maintenance based upon the maintenance schedule, while an unhealthy machine requiring servicing may be delayed in receiving maintenance simply because it was recently serviced.